Timing of lake-level changes for a deep last-glacial Lake Missoula: optical dating of the Garden Gulch area, Montana, USA

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Timing of lake-level changes for a deep last-glacial Lake Missoula: optical dating of the Garden Gulch area, Montana, USA. / Smith, Larry N.; Sohbati, Reza; Buylaert, Jan-Pieter; Lian, Olav B.; Murray, Andrew Sean; Jain, Mayank.

In: Quaternary Science Reviews, Vol. 183, 2018, p. 23-35.

Research output: Contribution to journalJournal article – Annual report year: 2018Researchpeer-review

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@article{76e485a90d43431b9d504fd3eb86be8c,
title = "Timing of lake-level changes for a deep last-glacial Lake Missoula: optical dating of the Garden Gulch area, Montana, USA",
abstract = "Glaciolacustrine sediments in the Clark Fork River valley at Garden Gulch, near Drummond, Montana, USA record highstand positions of the ice-dammed glacial Lake Missoula and repeated subaerial exposure. During these highstands the lake was at greater than 65{\%} of its recognized maximum capacity. The initial lake transgression deposited a basal sand unit. Subsequent cycles of lake-level fluctuations are recorded by sequences of laminated and cross laminated silt, sand, and clay deformed by periglacial processes during intervening periods of lower lake levels. Optically stimulated luminescence (OSL) dating of quartz sand grains, using single-aliquot regenerative-dose procedures, was carried out on 17 samples. Comparison of infrared stimulated luminescence (IRSL) from K-rich feldspar to OSL from quartz for all the samples suggests that they were well bleached prior to deposition and burial. Ages for the basal sand and overlying glaciolacustrine exposure surfaces are indistinguishable within one standard deviation, and give a weighted mean age of 20.9 ± 1.3 ka (n = 11). Based on sedimentological and stratigraphic analysis we infer that the initial transgression, and at least six cycles of lake-level fluctuation, occurred over time scales of decades to ∼2 ka. Bioturbated sandy slopewash dated at 10.6 ± 0.9 ka and 11.9 ± 1.2 ka unconformably overlies the upper glaciolacustrine deposits. The uppermost sediments, above the glaciolacustrine section, are younger than the Glacier Peak tephra (13.7-13.4 cal ka B.P.), which was deposited across parts of the drained lake basin, but has not been found at Garden Gulch. Our study indicates that glacial Lake Missoula reached >65 percent of maximum capacity by about 20.9 ±1.3 ka and either partially or completely drained twelve times from this position. Rapid lowering from the lake's highstand position due to ice-dam failure likely led to scour in the downstream portions of the glacial Lake Missoula basin and megafloods in the Channeled Scabland.",
keywords = "Glacial lake Missoula, North America, Optical dating methods, Periglacial, Quaternary",
author = "Smith, {Larry N.} and Reza Sohbati and Jan-Pieter Buylaert and Lian, {Olav B.} and Murray, {Andrew Sean} and Mayank Jain",
year = "2018",
doi = "10.1016/j.quascirev.2018.01.009",
language = "English",
volume = "183",
pages = "23--35",
journal = "Quaternary Science Reviews",
issn = "0277-3791",
publisher = "Pergamon Press",

}

RIS

TY - JOUR

T1 - Timing of lake-level changes for a deep last-glacial Lake Missoula: optical dating of the Garden Gulch area, Montana, USA

AU - Smith, Larry N.

AU - Sohbati, Reza

AU - Buylaert, Jan-Pieter

AU - Lian, Olav B.

AU - Murray, Andrew Sean

AU - Jain, Mayank

PY - 2018

Y1 - 2018

N2 - Glaciolacustrine sediments in the Clark Fork River valley at Garden Gulch, near Drummond, Montana, USA record highstand positions of the ice-dammed glacial Lake Missoula and repeated subaerial exposure. During these highstands the lake was at greater than 65% of its recognized maximum capacity. The initial lake transgression deposited a basal sand unit. Subsequent cycles of lake-level fluctuations are recorded by sequences of laminated and cross laminated silt, sand, and clay deformed by periglacial processes during intervening periods of lower lake levels. Optically stimulated luminescence (OSL) dating of quartz sand grains, using single-aliquot regenerative-dose procedures, was carried out on 17 samples. Comparison of infrared stimulated luminescence (IRSL) from K-rich feldspar to OSL from quartz for all the samples suggests that they were well bleached prior to deposition and burial. Ages for the basal sand and overlying glaciolacustrine exposure surfaces are indistinguishable within one standard deviation, and give a weighted mean age of 20.9 ± 1.3 ka (n = 11). Based on sedimentological and stratigraphic analysis we infer that the initial transgression, and at least six cycles of lake-level fluctuation, occurred over time scales of decades to ∼2 ka. Bioturbated sandy slopewash dated at 10.6 ± 0.9 ka and 11.9 ± 1.2 ka unconformably overlies the upper glaciolacustrine deposits. The uppermost sediments, above the glaciolacustrine section, are younger than the Glacier Peak tephra (13.7-13.4 cal ka B.P.), which was deposited across parts of the drained lake basin, but has not been found at Garden Gulch. Our study indicates that glacial Lake Missoula reached >65 percent of maximum capacity by about 20.9 ±1.3 ka and either partially or completely drained twelve times from this position. Rapid lowering from the lake's highstand position due to ice-dam failure likely led to scour in the downstream portions of the glacial Lake Missoula basin and megafloods in the Channeled Scabland.

AB - Glaciolacustrine sediments in the Clark Fork River valley at Garden Gulch, near Drummond, Montana, USA record highstand positions of the ice-dammed glacial Lake Missoula and repeated subaerial exposure. During these highstands the lake was at greater than 65% of its recognized maximum capacity. The initial lake transgression deposited a basal sand unit. Subsequent cycles of lake-level fluctuations are recorded by sequences of laminated and cross laminated silt, sand, and clay deformed by periglacial processes during intervening periods of lower lake levels. Optically stimulated luminescence (OSL) dating of quartz sand grains, using single-aliquot regenerative-dose procedures, was carried out on 17 samples. Comparison of infrared stimulated luminescence (IRSL) from K-rich feldspar to OSL from quartz for all the samples suggests that they were well bleached prior to deposition and burial. Ages for the basal sand and overlying glaciolacustrine exposure surfaces are indistinguishable within one standard deviation, and give a weighted mean age of 20.9 ± 1.3 ka (n = 11). Based on sedimentological and stratigraphic analysis we infer that the initial transgression, and at least six cycles of lake-level fluctuation, occurred over time scales of decades to ∼2 ka. Bioturbated sandy slopewash dated at 10.6 ± 0.9 ka and 11.9 ± 1.2 ka unconformably overlies the upper glaciolacustrine deposits. The uppermost sediments, above the glaciolacustrine section, are younger than the Glacier Peak tephra (13.7-13.4 cal ka B.P.), which was deposited across parts of the drained lake basin, but has not been found at Garden Gulch. Our study indicates that glacial Lake Missoula reached >65 percent of maximum capacity by about 20.9 ±1.3 ka and either partially or completely drained twelve times from this position. Rapid lowering from the lake's highstand position due to ice-dam failure likely led to scour in the downstream portions of the glacial Lake Missoula basin and megafloods in the Channeled Scabland.

KW - Glacial lake Missoula

KW - North America

KW - Optical dating methods

KW - Periglacial

KW - Quaternary

U2 - 10.1016/j.quascirev.2018.01.009

DO - 10.1016/j.quascirev.2018.01.009

M3 - Journal article

VL - 183

SP - 23

EP - 35

JO - Quaternary Science Reviews

JF - Quaternary Science Reviews

SN - 0277-3791

ER -